CATV networks use an infrastructure of interconnected coaxial cables, signal splitters and combiners, repeating amplifiers, filters, trunk lines, cable taps, drop lines and other signal-conducting devices to supply and distribute high frequency “downstream” signals from a main signal distribution facility, known as a “headend,” to the premises (e.g., homes and offices) of CATV subscribers. The downstream signals operate the subscriber equipment, such as television sets, telephone sets, and computers. In addition, most CATV networks also transmit “upstream” signals from the subscriber equipment back to the headend of the CATV network. For example, the subscriber uses a set top box to select programs for display on the television set. As another example, two-way communication is essential when using a personal computer connected through the CATV infrastructure to the public Internet. As a further example, voice over Internet protocol (VOIP) telephone sets use the CATV infrastructure and the public Internet as part of the communication medium for two-way telephone conversations.
To permit simultaneous communication of upstream and downstream CATV signals, and to permit interoperability of the subscriber equipment and the equipment associated with the CATV network infrastructure outside of subscriber premises, the downstream and upstream signals are confined to two different frequency bands. For example, in some CATV networks the downstream frequency band can be within the range of 54-1002 megahertz (MHz) and the upstream frequency band can be within the range of 5-42 MHz.
The downstream signals are delivered from the CATV network infrastructure to the subscriber premises at a CATV entry adapter, which is also commonly referred to as an entry device, terminal adapter, or a drop amplifier. The entry adapter is a multi-port device which connects at an entry port to a CATV drop cable from the CATV network infrastructure and which connects at a multiplicity of other distribution ports to coaxial cables which extend throughout the subscriber premises to cable outlets. Each cable outlet is available to be connected to subscriber equipment. Typically, most homes have coaxial cables extending to cable outlets in almost every room, because different types of subscriber equipment may be used in different rooms. For example, television sets, computers, and telephone sets are commonly used in many different rooms of a home or office. The multiple distribution ports of the entry adapter deliver the downstream signals to each cable outlet and conduct the upstream signals from the subscriber equipment through the entry adapter to the drop cable of the CATV infrastructure.
In addition to television sets, computers and telephones, a relatively large number of other entertainment and multimedia devices are available for use in homes. For example, a digital video recorder (DVR) is used to record broadcast programming, still photography and moving pictures in a memory medium so that the content can be replayed on a display or television set at a later time selected by the user. As another example, computer games are also played at displays or on television sets. Such computer games may be those obtained over the Internet from the CATV network or from media played on play-back devices connected to displays or television sets. As a further example, signals from a receiver of satellite-broadcast signals may be distributed for viewing or listening throughout the home. These types of devices, including the more-conventional television sets, telephone sets, and devices connected to the Internet by the CATV network are generically referred to as multimedia devices.
The desire to use multimedia devices at multiple different locations within the home or subscriber premises has led to the creation of the Multimedia over Coax Alliance (MoCA). MoCA has developed specifications for products to create an in-home entertainment network for interconnecting presently-known and future multimedia devices. A MoCA in-home network uses the subscriber premise or in-home coaxial cable infrastructure originally established for distribution of CATV signals within the subscriber premises, principally because that coaxial cable infrastructure already exists in most homes and is capable of carrying much more information than is carried in the CATV frequency bands. A MoCA network is established by connecting MoCA-enabled or MoCA interface devices at the cable outlets in the rooms of the subscriber premises. These MoCA interface devices implement a MoCA communication protocol which encapsulates the signals normally used by the multimedia devices within MoCA signal packets and then communicates the MoCA signal packets between other MoCA interface devices connected at other cable outlets. The receiving MoCA interface device removes the encapsulated multimedia signals from the MoCA signal packets, and delivers the multimedia signals to the connected display, computer, or other multimedia device from which the content is presented to the user.
Each MoCA-enabled device is capable of communicating with every other MoCA-enabled device in the in-home or subscriber premises MoCA network to deliver the multimedia content throughout the home or subscriber premises. The multimedia content that is available from one multimedia device can be displayed, played, or otherwise used on a different MoCA enabled device at a different location within the home, thereby avoiding physically relocating the originating multimedia device from one location to another within the subscriber premises. The communication of multimedia content over the MoCA network is considered beneficial in more fully utilizing the multimedia devices present in modern homes.
A MoCA network can potentially leak signal out of the subscriber premises via the CATV entry adapter. The leaked signal can be received by a neighboring home also using MoCA, which can cause interference, privacy, and security issues. To avoid such leakage, a MoCA filter can be installed at the CATV entry adapter.